Add explanatory comment for why hex float literals use 64 bits.
Add explanatory comment for why hex float literals use 64 bits.


Former-commit-id: 4c7572be88f1c4e687d62e58280c226114d3412f
darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide